The present invention relates to a method and apparatus for reestablishing the spinning operation of a spinning station of an open end spinning machine and more particularly for reestablishing spinning after either a yarn break or a package change.
Frameless service units are conventionally used for changing packages at spinning stations of spinning machines for empty tubes. One type of such unit performs the package change by severing the yarn being fed from the spinning element to the package being wound, retaining the continuously feeding yarn in a suction tube and changing the full package for an empty tube. Thereafter, the yarn that has been continuously drawn into the suction tube is transferred to the tube where, initially, a yarn reserve on an extension of the tube is built, and then the yarn is released for continuous spinning at the spinning station.
However, one disadvantage of this type of package change operation is that the yarn continues to feed from the spinning element while the package change unit, which serves a plurality of spinning stations, travels to the spinning station to carry out the package changing operation. Typically, the package changing unit is summoned to service a spinning station when the yarn being wound on the package thereat has reached a predetermined length or the package has reached a predetermined mass or a predetermined diameter. In order to build a package having a relatively precisely predetermined yarn length, the spinning operation must be immediately interrupted once the yarn length is reached, at which time the servicing unit may not be readily available.
Also known are combination package changing and yarn restarting units which, after performing a package changing operation, restart the spinning operation using an auxiliary yarn to provide a yarn end to feed to the spinning element. The newly spun yarn is pieced onto the auxiliary yarn and is drawn out of the spinning element by suction and transferred to the empty tube for building a package thereon.
However, the productivity using such a combination unit is relatively low because during the restoring of a spinning station to its spinning operation following a yarn break, the package change apparatus must necessarily remain idle and is, accordingly, not available to service other spinning stations at the same time that the yarn restart apparatus is restoring the one spinning station to its spinning operation. The capacity of such a combination apparatus to execute package changing operations is especially limited if the package changing component thereof includes an apparatus for preparing yarn end of the finished package which thereby extends the cycle time for the package changing operation. In this event, it is especially necessary to provide several combination package changing and yarn restarting units for a single open end spinning machine with a corresponding expense and complication.
Also known are systems having a higher package changing capacity by having the package changing apparatus and the yarn restarting apparatus independently movable for independently servicing the spinning stations. The package changing unit of this type of system carries the empty tubes for the package changing operation itself and these tubes have previously been provided with a start-up length of yarn for piecing with new yarn in the spinning element to start the spinning and winding onto the tube. As can be understood, once a so-called starter tube has been disposed on the creel of a spinning station, the yarn restarting operation proceeds in the same manner as if a yarn break had occurred at the spinning station. These types of systems have been used to accomplish batch changings. However, this type of system requires the expense and complication of prior processing of tubes to provide the start-up end.
Accordingly, the need exists for a package changing and a yarn restarting arrangement for a spinning machine which maximizes efficient use of each operation for performing its particular function at the spinning machine.